1. Field of the Invention
The present invention relates to a method and system for spinal fixation, stabilization and/or fusion of the human occipito-cervical junction. Additionally, the invention is further directed to a method and apparatus for the treatment of an abnormal neuraxial angle, abnormal clivo-axial angle and mitigation of neurological conditions underlying neurobehavioral disorders arising as a result of abnormalities of the neuraxial angle, clivo-axial angle, skull base, craniocervical, posterior fossa and combinations thereof, which, without wishing to be bound by theory in a subset of individuals, cause neuro-behavioral disorders such as autism, autism spectrum of disorders, bipolar disorder and other neurological disorders. The present invention is directed to the treatment of these neurological disorders through the recognition, diagnosis, normalization of the craniospinal relationship by fixation, stabilization and/or fusion of the human occipito-cervical junction.
2. Description of the Related Technology
The normal range of motion of the craniospinal junction includes about 27° of flexion and extension, and 90° of lateral rotation; the craniospinal junction is thus the most mobile and articulatable part of the human body. It is also the most active part of the human body in movement throughout the day, typically performing greater than 3 million motions a year. The craniospinal junction transmits the entire nervous structure to the body (with the exception of the vague nerve), and is thus unfortunately susceptible to a host of degenerative disorders. Other common causes of cranio-cervical instability, include traumatic fractures, which can account for approximately 3,000 fractures of the upper spine related to head trauma each year; congenital diseases, such as Ehlers Danlos syndrome, Down's syndrome, Morquio's syndrome and spondyloepiphysial dysplasia syndrome, with a prevalence of at least 50,000; and osteogenesis imperfecta, with a prevalence of 7,000 patients. There are numerous causes of bone softening related to malabsorption syndromes and other renal/metabolic and endocrine syndromes that result in abnormal craniospinal relationships. Additionally, cancer and infections that involve the craniocervical junction. can cause destruction of the stabilizing elements.
Among the patients suffering from craniocervical abnormalities, are subsets of individuals diagnosed with neurological disorders, such as sleep apnea, dyslexia, GERDS, speech dyspraxia, idiopathic scoliosis, and neuropsychiatric disorders, such as autism spectrum of disorders (eg. Asperger's Syndrome), Attention Deficit Hyperactivity Disorder, scizophrenia, bipolar disease, depression and anxiety disorders. The neurological and neurosurgical literature has reported instances where neurological symptoms appear to have been associated with retroflexion of the odontoid, platybasia and select forms of basilar invagination. The clivioaxial angle is depicted in FIG. 1, while an example of basilar invagination causing visible compression of the brainstem is shown in FIG. 2, which has been associated with sleep apnea, delayed speech, gastroesophageal reflux, and altered behavior, such as attention deficit disorder, headaches, and a myriad of other sensori-motor syndromes. Additionally, the presence of a Chiari malformation has been associated with scoliosis, GERDS, sleep apnea and unusual neurological findings such as trigemenial neuralgia, and tongue thrusting. The prior art, however, has yet to recognize a relationship between deformative stress of the brainstem and neurobehavioral disorders or contemplate treatment of a neurological disorder by reducing or eliminating the deformative stress.
A need exists for a system and methodology that accomplishes the goals of recognition of the subtler forms of craniocervical and corresponding medullospinal deformity as a cause of neurological disorders and conditions, measurement of the deformity, and the reduction or correction of deformity through normalization of the craniospinal relationship to effectively treat the neurological disorders.